1. Field of the Invention
The invention concerns a hydraulic damping cartridge as outlined by the claims.
2. Description of Related Art
There are numerous known solutions in the market, in which a damping cartridge is constructed with an adjustable rebound stage damping. Higher quality hydraulic damping cartridges are also fitted with an additional adjustable compression stage damping unit, so that a suspension fork (air spring or mechanical spring) fitted with such a damping cartridge can be flexibly adjusted to different conditions of use.
The damping of such damping cartridges is in principle achieved using a pressure medium, preferably oil, which is forced through choke valves during compression and extension strokes, whereby the choke valve cross section of these choke valves can be varied. The displaced pressure medium is moved to a compensating volume or is fed from this. For this, most scenarios rely on a gas or an air cushion, which is separated from the pressure medium by means of an internal floating piston or which is located in a compensating volume into which the pressure medium is displaced. Solutions with internal floating pistons require considerable technical costs in manufacturing. Solutions without physical separation of air and pressurizing medium run the risk of both media become mixed or of the pressure medium foaming with an accompanying deterioration of the damping function.
Especially with longer travel suspension forks (with 130 mm stroke or longer) it is important to prevent an uncontrolled sagging on the compression stroke. This is achieved by means of an adjustable compression stage damping, which can be externally adjusted to change the damping characteristics.
Known damping cartridges with adjustable rebound and compression stage damping are, as a rule extremely complex constructions and are not suited for retro-fitting to existing suspension forks.